walls

A wall is a structure that defines an area, carries a load, or provides shelter or security. There are many kinds of walls:
Defensive walls in fortification
Walls in buildings that form a fundamental part of the superstructure or separate interior sections, sometimes for fire safety
Retaining walls, which hold back dirt, stone, water,or noise sound
Walls that protect from oceans (seawalls or rivers levees)
Permanent, solid fences
Border barriers between countries
Brick wall
Stone wall
Glass wall (only when most of the wall, in smaller amounts it is called a window)
Doors are mobile walls on hinges which open to form a gateway